I. Field
The present invention relates generally to circuits, and more specifically to an inductor for an integrated circuit and a printed circuit board.
II. Background
With modern advances in integrated circuit (IC) process technology, it is possible to fabricate radio frequency integrated circuits (RFICs) for numerous applications such as wireless communication, networking, computing, and so on. These RFICs may include various analog circuit blocks that were previously implemented with bulky discrete circuit components. By implementing analog circuit blocks on RFICs, various benefits such as smaller size, lower cost, and improved reliability can be realized.
Many analog circuit blocks utilize reactive components such as capacitors and inductors to achieve the designed functions. For example, filters, resonator tanks, impedance matching networks, and so on may include both capacitors and inductors to obtain the desired circuit response. For some applications, such as a tank circuit for a voltage controlled oscillator (VCO), it is necessary to vary a reactive component over a specified range of value. If adjusting capacitance is acceptable, then a variable capacitor (also referred to as a “varactor”) is often used as the variable reactive component. In certain applications, it is necessary or desirable to adjust inductance instead of capacitance. For these applications, a bank of inductors (each coupled in series with a respective switch) is conventionally used to obtain different inductance values by switching on the proper inductor or combination of inductors in the bank. However, the bank of inductors occupies a large area, which translates into higher cost. Moreover, the series-coupled switch can degrade the performance of the inductor.
There is therefore a need in the art for an adjustable inductor that can be fabricated on an integrated circuit.